The invention relates to a device for automatically injecting injection liquids, including an axially subdivided housing whose parts are detachably connectable, wherein an axially displaceable pressure pin is guided in a first housing part, which pin is capable of being inserted against a force accumulator and locked in the inserted position and extended upon relief of said force accumulator, and wherein an injection needle fitted within a needle guide and an ampoule are mounted in a second housing part in an axially displaceable manner.
Devices of the initially mentioned kind have become known as autoinjectors. The known devices are pen-sized instruments which facilitate the injection of an emergency agent into the body in the event of an emergency situation. Autoinjectors are employed, for instance, in allergic emergency situations, e.g., in the event of insect or snake bites etc., but also in the military field, for instance, in order to rapidly counteract intoxications by C warfare agents. The known devices are usually designed as disposable devices, thus being disposed of after a one-time use.
From AT 303 251, an injection device is known, which comprises two housing parts capable of being screwed one into the other, the activator containing a spring-loadable pressure pin and the injector containing the ampoule as well as the injection needle as an inseparable unit. After having unlocked the spring-loaded pressure pin, the latter exerts a force on the piston plug of the ampoule, whereupon, at first, the ampoule is displaced in the axial direction together with the injection needle within the injector housing so as to cause the injection needle to penetrate into the body surface, and the liquid contained in the ampoule is subsequently set under such a high pressure that a sealing membrane provided between the ampoule and the injection needle will break, thus causing the liquid to be ejected. That known configuration, however, has the drawback that the broken membrane may obstruct the injection needle, thus preventing the rapid ejection of the injection liquid. Furthermore, that configuration constitutes a problem connected with the disposal of the autoinjector after use, since the injection needle projects out of the housing and, thus, constitutes a high risk of injury and infection.
The previously known autoinjectors, furthermore, have the drawback of rendering the safe storage and transportation of stand-by ampoules unfeasible. The ampoule can be inserted into the autoinjector only at works. Moreover, with the known autoinjectors, another whole autoinjector must always be taken along as a stand-by autoinjector.
The invention aims to provide a device of the initially defined kind, which can be disposed of without any risk of injury or infection and the disposal of which, in addition, is feasible in as environmentally safe a manner as possible by minimizing the number of parts to be disposed of. At the same time, the invention aims to provide a storing and transporting container for the ampoules, in which the filled glass ampoule can be stored over years in a safely protected and tightly sealed manner. In particular, it is to be feasible to carry along several ampoules containing different injection liquids and/or stand-by ampoules while minimizing the parts to be carried along. To solve this object, the device according to the invention essentially consists in that the injection needle fitted in the needle guide is mounted so as to be displaceable in the axial direction relative to the ampoule and, on its side facing the ampoule, is designed as a perforation piece for the ampoule, and that the second housing part, on its open end facing the first housing part, is closable by a sealing cap. By designing the injection needle as a perforation piece for the ampoule on its side facing the ampoule and mounting the injection needle so as to be displaceable in the axial direction relative to the ampoule, it is feasible to mount the ampoule in the interior of the second housing part, i.e., the injector, without being firmly connected with the injection needle. The injection liquid may, thus, be safely stored in the ampoule over years without the ampoule being firmly connected with any of the other structural components and the stability of the injection liquid being negatively affected. The use of an ampoule, moreover, substantially facilitates the manufacture of the injector part and, in addition, offers the advantage that a larger selection of different injection liquids will be available than with ready-made syringes.
It is only in use that the ampoule is displaced in the direction of the injection needle under the force of the pressure pin extended upon relief of the force accumulator, and pierced by the injection needle designed as a perforation piece on its side facing the ampoule. Thereby, any obstruction of the injection needle will be reliably prevented and it will be ensured that the injection liquid may leave the ampoule unhampered, after the injection needle has been pushed out of the injector housing and penetrated the tissue.
By making the second housing part closable by a sealing cap on its open end facing the first housing part, a storing and transporting container for the glass ampoule as well as a disposal container for the used injection needle and the empty ampoule is simultaneously provided. The housing part enclosing the ampoule and the needle may, thus be stored and transported separately from the activator part, the ampoule and the needle being protected in a breakage-proof manner and sealed in a bacteria-tight manner over years by means of the sealing cap. Thus, the carrying along of several different ampoules is, above all, facilitated. The activator part which can be carried along separately may be connected with the injector part containing the respective injection liquid according to demands. The carrying along of several activator parts is not necessary, since the activator is reusable.
The housing part enclosing the needle will be even more suitable for use as a disposal container, if the ampoule and/or the needle guide are advantageously mounted in a resilient manner. After the use of the autoinjector, the injector part is detached from the activator with the used injection needle projecting out of the injector housing automatically getting back into the interior of the housing due to the action of a resilient component. In this context, the configuration may be devised such that a helical spring is arranged in the interior of the second housing part between the housing end including the passage opening for the injection needle and the needle guide. Due to the fact that the second housing part, on its end including the passage opening for the injection needle, is advantageously closed by an elastic sealing disc, the needle-side end of the injector housing will always remain tight such that no sealing cap need be slipped on.
If the use of a resilient component acting on the needle guide or the ampoule is obviated, the injection needle may be pushed back into the housing after the use of the autoinjector by putting or screwing a sealing cap on that end of the second housing part out of which the used injection needle projects. The injector will be closed in any event on its open end facing the first housing part, i.e., the activator, thus forming a disposal container safely and sealingly receiving the used injection needle and the empty ampoule. Any injury or infection by the disposed parts is thereby excluded, and the number of parts to be thrown away is further minimized. As a result, the activator may be reused by inserting the pressure pin against a force accumulator and locking it in the inserted position and connecting the activator with a new injector. A new, unused injector will always be closed by a sealing cap prior to its first use, thus providing a storing and transporting container for the glass ampoule, by which the sterility of the ampoule and the needle unit will be safeguarded. Consequently, several injectors containing different injection liquids may, for instance, be carried along with the appropriate injector being connectable to the activator upon detachment of the sealing cap in an emergency case.
As already mentioned, the device according to the invention is devised such that the injection needle carrying the perforation piece for the ampoule is mounted so as to be axially displaceable relative to the ampoule by a needle guide. It is thereby ensured that the injection needle mounted so as to be axially displaceable by a needle guide, upon the action of force by the pressure pin on the piston of the ampoule, will, at first, be displaced in the axial direction and penetrate the tissue through the skin on the desired site, and the perforation piece of the injection needle will break the ampoule only after this, wherein the needle guide, on its jacket, advantageously comprises at least one inwardly salient resilient abutment piece for the ampoule and, furthermore, at least one outwardly salient resilient abutment piece which cooperates with an appropriate stop of the second housing part. The inwardly salient resilient abutment piece is dimensioned so as to offer a higher resistance against the force exerted by the pressure pin than the outwardly salient resilient abutment piece. As a result, the injection needle will, at first, penetrate the interior of the body while overcoming the force of the outwardly salient resilient abutment piece bending back in the direction towards the ampoule, whereupon the inwardly salient resilient abutment piece is being pushed inwardly into the needle guide as the perforation piece passes into the ampoule. Due to the outwardly salient resilient abutment piece cooperating with an appropriate stop of the second housing part in the transport and storage position, the needle guide can be precisely positioned and received within the housing in a manner secured in its position.
Advantageously, the device according to the invention is designed such that the sealing cap carries a thread or a bayonet capable of being screwed or latched with a counter-thread or counter-bayonet, respectively, provided on the open end of the second housing part.
In order to reliably prevent the ampoule from falling out of the second housing part after having been separated from the activator part, the configuration advantageously is devised such that a piece comprising a stop for the ampoule is lockable in a second housing part region that is designed to have an enlarged diameter, thus securing the ampoule against falling out. On account of the force of the expanding pressure spring acting on the needle guide, it is, thereby, safeguarded that neither the contaminated injection needle nor the then empty ampoule will fall out or be flung out of the second housing part.
Furthermore, the device according to the invention in a particularly advantageous manner is designed such that the counter-thread provided on the open end of the second housing part is capable of being screwed with a thread of the first housing part. This enables the counter-thread provided on the second housing part to be screwed with the sealing cap, on the one hand, and, upon detachment of the sealing cap, with the activator, on the other hand.